1. Field of the Invention
This invention relates to antisweat heater structures and in particular to antisweat heaters for use in refrigeration apparatus cabinets and the like.
2. Description of the Background Art
In one form of refrigeration apparatus cabinet, a mullion extends across the refrigerated space so as to form separated compartments within the outer cabinet. Conventionally, the mullion divides the refrigerated space into a freezer compartment and a fresh food above-freezing compartment. The mullion may extend horizontally so as to provide vertically related compartments, or vertically so as to provide side-by-side related compartments.
One example of such a refrigeration apparatus having a vertical mullion to provide side-by-side freezer and fresh food compartments is illustrated in U.S. Letters Pat. No. 3,939,666 of Larry T. Bashark, which patent is owned by the assignee hereof. As shown therein, it is conventional to provide stile and mullion heaters for controlling condensation on the edge of the mullion and cabinet walls defining the refrigerated space normally closed by suitable doors. In the Bashark patent, a control is provided for selectively energizing the stile and mullion heaters with full operating current, or only one of the heaters at a reduced current, depending on the sensed humidity and temperature conditions.
The heaters conventionally provided for such antisweat functioning are relatively low wattage heaters so as to effectively minimize energy loss in eliminating condensation of moisture on the exposed wall surfaces. Further illustratively, it is conventional to provide the stile heater only about the freezer compartment where a greater problem of condensation is found.
The conventional stile and mullion heaters utilize a heater cable having a generally constant value of resistance per unit length of cable that will produce heat uniformly along the longitudinal extent thereof.
It has been found that such resistance heaters do not provide proper distribution of the heating corresponding to the areas of greater condensation formation. Illustratively, it has been found that greater concentration of the condensation occurs at the junction of the mullion and outer cabinet walls.
One attempted solution to the problem has been to concentrate heat in the area of this junction by looping the stile heater cable back and forth several times adjacent the junction. It has been found, however, that the required supplemental heat at this point necessitates the use of an excessive looping of the stile heater, effectively precluding a satisfactory solution in this manner. Another problem from such a substantial looping of the heater cable is the substitution thereof for the foam insulation at this point, further aggravating the heat transfer problem causing the condensation deposit.